it's not rocket science. it's just common sense. from td ameritrade. >>> on capitol hill today the man who runs nasa was asked, what could be done if a large meteor were headed for new york city? his answer? pray. cnn's chris lawrence has more on today's hearings. pretty scary stuff going on, chris. >> you said it, wolf. the only reason people aren't scared out of their minds is the fact that it's so rare for one of these big rocks to hit the earth. but look. there are 10,000 to 20,000 asteroids out there big enough to devastate a continent and only 10% have been detected. russians saw a flash of light and heard the sonic boom. the meteor exploded with the force of a nuclear bomb. it did $30 million in damage and injured thousands. and no one saw it coming. >> we were fortunate that the events of last month were simply an interesting coincidence rather than a catastrophe. >> reporter: the nation's top science officials were called before congress tuesday to explain what they're doing to detect similar threats from space. >> objects